SENEGAL BICHIR (Polypterus senegalus)

An incredibly hardy, nocturnal species with very poor vision, P. senegalus relies on its excellent sense of smell to locate food. This species, along with others of its genus, are some of the last surviving relatives of very ancient species. Fossils of earlier relatives have been found that date back to the Triassic Period, which occured during the early development of the dinosaurs more than 200 million years ago.

They have several interesting adaptations. The swim bladder is divided into 2 parts, of which the right hand section is considerably larger. This functions as an accessory breathing organ and means the fish can survive out of water for some time, provided it is kept moist. Like Ananbantoid species, this fish may actually drown if it is denied access to atmospheric air.
Young bichirs have amphibian-like external gills which are lost as the fish matures. This, coupled with their nocturnal mode of hunting, in which they emerge from their daytime refuges to hunt invertebrates and small fish in shallow water clearly exhibit the link these species form between fish and amphibians.

https://www.seriouslyfish.com/species/polypterus-senegalus-senegalus/